1. Field of the Invention
The present invention relates in general to a method and apparatus to seal between wellbore members, and in particular to a metal seal used between two members of an adjustable wellbore casing.
2. Brief Description of Related Art
An adjustable casing sub (“ACS”) can be used when connecting a drilling platform to an existing wellhead. For example, a “jack-up” or fixed oil and gas platform can be re-connected to a previously installed subsea wellhead or mudline system. The ACS is part of a riser assembly that provides for an adjustable length. The ACS can include two concentrically located tubular members. The tubular members can move axially in relation to each other, and then be sealed together when they are at the desired length.
The tubular members can have a housing annulus, or seal pocket, wherein an annular gap is located between the outer diameter of the inner tubular member and the inner diameter of the outer tubular member. A seal can be placed in the housing annulus. Existing ACS designs use an elastomeric annular seal arrangement, which can have inherent limitations when used in a high pressure or high temperature application.
There are numerous ACS systems in inventory, and thus it is not practical to redesign the housing annulus itself to use a seal that is more compatible with high pressure and high temperature environments. Therefore, it is desirable to have a metal seal that can work within the existing housing annulus design and form a seal between the metallic tubular members.